A specialized type of heater apparatus is necessary for use on natural gas pipelines. The need for such heaters arises when there is a reduction in the pressure of the natural gas within the pipeline, such as is typically the case when a percentage of the gas in a main line is diverted to a separate pipeline to service a municipality, or the like. The sudden loss in internal pipeline pressure results in potential undesirable condensation of hydrocarbons in the pipeline, potentially resulting in obstruction or faulty flow of gas. This possible condensation problem is avoided by heating the pipeline through the use of the specialized pipeline heater.
Pipeline heaters are typically needed in locations along the pipeline that are remote, often being without any electrical supply available to operate the heater. Typical types of such heaters include indirect or dehydration heaters, most often heating a heat-transferring substance, such as glycol, by a gas burner. The gas burner is ignited by a pilot light, the pilot light being a smaller gas burning flame.
The types of such heaters in use today often include manually operated pilot flame ignition, without safety features for providing reliable relighting of an extinguished pilot or main burner shut-off features. Therefore, the burners presently being used are not reliable for avoiding hydrocarbon condensation in the pipeline, and do not have much needed safety features for detecting and reacting to burner pilot flame failure. Further, the burners presently used have continual pilot flames, regardless of infrequent burner use, resulting in wasted fuel of unnecessary pilot burn time.
Also, the burners presently in use have a pilot assembly having a structure which have an ignitor terminal extending into the pilot flame, resulting in deterioration of the ignitor terminal due to constant exposure in the pilot flame and/or loss of the important tolerance of the spacing of the ignitor terminal to the area of the pilot for conducting spark.
The present invention resolves these problems in the field, primarily by providing a specific structure of a pilot assembly, and by providing a pilot control means which optionally provides a continuous burning pilot or provides an on-demand pilot, both such pilot operations having safety features for shutting down the main burner valve and relighting the pilot, in the event it is extinguished.